Mirror baryonic matter has been advocated to explain partially or even totally the nature of DM, in the context of the \(Z_2\) -symmetric mirror world (see e.g. [1]}). This may be achieved, in spite of the lower temperature of the mirror world, by means of a proper baryogenesis mechanism in the mirror sector [2]}.
In the following, we will not dwell with mirror baryonic DM (which is assumed to give a negligible contribution
due to the lower temperature of the SM mirror copies) and focus instead on axionic DM.
